Linux Kernel up to 6.12.96/6.18.39/7.1.4 synproxy tcp_parse_options/synproxy_parse_options timestamp stack-based overflow

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
6.2	$5k-$25k	0.00

Summaryinfo

A vulnerability described as critical has been identified in Linux Kernel up to 6.12.96/6.18.39/7.1.4. This issue affects the function tcp_parse_options/synproxy_parse_options of the component synproxy. The manipulation of the argument timestamp results in stack-based overflow. This vulnerability is identified as CVE-2026-80637. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability classified as critical has been found in Linux Kernel up to 6.12.96/6.18.39/7.1.4. Affected is the function tcp_parse_options/synproxy_parse_options of the component synproxy. The manipulation of the argument timestamp with an unknown input leads to a stack-based overflow vulnerability. CWE is classifying the issue as CWE-121. A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function). This is going to have an impact on integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: netfilter: synproxy: fix unaligned memory access in timestamp adjustment Use get_unaligned_be32() and put_unaligned_be32() to safely read and write the timestamp fields. This prevents performance degradation due to unaligned memory access or even a crash on strict alignment architectures. This follows the implementation of timestamp parsing in the networking stack at tcp_parse_options() and synproxy_parse_options().

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2026-80637 since 08/26/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 08/28/2026).

Upgrading to version 6.12.97, 6.18.40 or 7.1.5 eliminates this vulnerability. Applying the patch 2b8e7aaa38002d8ee2f48d87b1f392eadd8e98c4/5c9c67cf7a3d16051dfb90e98836f530964dfb8e/ea3d2caa5bfacf5db5c1cad521ca5d9144edd9a7/992c20bc8a4aba220c8b95b467d049289778dad6 is able to eliminate this problem.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.12.0
• 6.12.1
• 6.12.2
• 6.12.3
• 6.12.4
• 6.12.5
• 6.12.6
• 6.12.7
• 6.12.8
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• 6.12.90
• 6.12.91
• 6.12.92
• 6.12.93
• 6.12.94
• 6.12.95
• 6.12.96
• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
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• 6.18.33
• 6.18.34
• 6.18.35
• 6.18.36
• 6.18.37
• 6.18.38
• 6.18.39
• 7.1.0
• 7.1.1
• 7.1.2
• 7.1.3
• 7.1.4

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.5
VulDB Meta Temp Score: 6.2

VulDB Base Score: 6.5
VulDB Temp Score: 6.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Stack-based overflow
CWE: CWE-121 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.12.97/6.18.40/7.1.5
Patch: 2b8e7aaa38002d8ee2f48d87b1f392eadd8e98c4/5c9c67cf7a3d16051dfb90e98836f530964dfb8e/ea3d2caa5bfacf5db5c1cad521ca5d9144edd9a7/992c20bc8a4aba220c8b95b467d049289778dad6

Timelineinfo

08/26/2026 CVE reserved
08/28/2026 +2 days Advisory disclosed
08/28/2026 +0 days VulDB entry created
08/28/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-80637 (🔒)
GCVE (CVE): GCVE-0-2026-80637
GCVE (VulDB): GCVE-100-396576

Entryinfo

Created: 08/28/2026 10:30
Changes: 08/28/2026 10:30 (60)
Complete: 🔍
Cache ID: 216::103

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